I have a 99 5.4l that the sevice engine light came on. I took it to autozone and the code was PO402 which is exsessive flow. I had them clear the code and it has not returned yet. Should I go ahead and change the EGR valve or wait and see? The truck is running great. The EGR valeve vacum connections are good and the hose looks in good order. So any tips would be helpful.

Thanks

 

Had the same problem 3 weeks ago. Changed the EGR valve per dealer, week latter got code 401. Asked here on the board and was told to check the DPFE voltages, they were not out, but close. I changed it and code has not come back. Truck ran fine before and seems to be the same as before. I have 60,000 miles, 5.4l, F150.

long and short, I would check voltages of DPFE first, possibly change, than if you continue to get the code consider the EGR valve first. Just my opinion.

Good luck.

Dave

 

I will give it a try tomorrow. Right now there is no light, but we will see if that holds true. I have found the DPFE and will check the voltages per the haynes manual.

Thanks for the tip it makes more sense that the electric controller would fail before a diaphramed sensor. More to go wrong.
I will let you know how things work out.

Bill